Boron redox reactions

A series of divalent lanthanide metal metaHaborane derivatives have been prepared by the redox reaction of metallic lanthanides and boron hydrides and by the metathesis reaction of boron hydride salts with LnCl2 where Ln = Sm, Eu, Yb (181,182). The species (CH3CN)3Yb[(p.-H)2B2QH22],... 

C21-0008. Sulfur tetrafluoride fluorinates boron trichloride according to the following unbalanced equation BCI3 + SF4 BF3 + SCI2 + CI2 This is both a redox reaction and a metathesis reaction, (a)... 

Some of the investigations carried out in the first half of the twentieth century were related to CL associated with thermal decomposition of aromatic cyclic peroxides [75, 76] and the extremely low-level ultraviolet emission produced in different reaction systems such as neutralization and redox reactions involving oxidants (permanganate, halogens, and chromic acid in combination with oxalates, glucose, or bisulfite) [77], In this period some papers appeared in which the bright luminescence emitted when alkali metals were exposed to oxygen was reported. The phenomenon was described for derivatives of zinc [78], boron [79], and sodium, potassium, and aluminum [80]. 

The first borinate-transition metal complex to be prepared was actually the first known derivative of borin. Bis(cyclopentadienide)cobalt (94) reacts with organic halides and was analogously found to react with boron halides in a redox reaction to give (95), followed by an insertion to yield (cyclopentadienide)(borinato)cobalt (97) (72CB3413). The product composition depends on the ratio of reactants. Compound (97) is the main product (80% yield when R = Ph, X = Br) when the molar ratio between (94) and the boron halide is 2.5 1. A second and slower insertion occurs to give (28) when (97) is treated with another equivalent of the boron halide (Scheme 13). Compounds (28), (29) and (97) have one electron more than predicted by the 187r-electron rule for transition metal complexes. They are red in colour and, of course, paramagnetic. The mixed complexes (97) are thermally labile, in contrast to (28) and (29), which can be heated to 180 °C and sublimed at 90 °C. Their ionization potentials are low and the complexes are sensitive to air. 

Bayer and Siebert reported the reaction of 3,3-dimethyl-l-butyne with -BuLi in pentane, followed by the addition of boron trichloride to afford the intermediate dichloro(3,3-dimethylbut-l-ynyl)borane that was hydroborated with dichloroborane formed in situ to give l,l-bis(dichloroboryl)-3,3-dimethylbutene 51 (Scheme 6) <2002ZN1125>. When the latter was subjected to halogen exchange with boron triiodide, it was converted into the corresponding tetraiodide 52, which underwent a redox reaction with hex-3-yne to give the 2-(2,2-dimethylpropylidene)-l,3-diborole 22 in 73% yield. 

Boronate Esters to Detect ROSs Many small-molecule fluorescent ROS probes have been reported in the fiteratnre which consist of a reduced form of a fluo-rophore. Upon redox reaction with a reactive small molecule, the fluorescence... 

Boron-carbon bonds can be formed by redox reactions between boron iodides and organic iodides, e.g. ... 

Fusion processes can be grouped into acid-base reactions (carbonates, borates, hydroxides, disulfates, fluorides, and boron oxide) and redox reactions (alkaline fusion agent plus oxidant or reductant). Common fluxes are listed in Table 4.2. Fluoride-pyrosulfate and carbonate-bisulfate fusions are used to decompose soil and fecal samples. 

Another reason for the poor sinterability is the extraordinarily high vapor pressure of boron oxides and suboxides. Since boron carbide powders are generally coated by a B2O3 layer [172] which quickly reacts to form boric acid, H3BO3, in humid atmosphere, vapor phase reactions are active at higher temperatures, in particular above 1500"C, providing a fast transport of boron compounds. Redox reactions such as... 

A subsequent one-electron transfer occurs at more positive potentials, 0.9 V, to form the dication, CPZ", which is quickly hydrolyzed [179]. The electrode reaction kinetics for this redox system (CPZ/CPZ ) at diamond are mainly influenced by the density of electronic states at the formal potential [22,30]. Rapid electrode-reaction kinetics have been observed for boron-doped diamond electrodes, with no evidence of any molecular adsorption [22,30]. The QS jQp ratio for the CPZ/CPZ redox reaction is ca. 1. The ip and ip values varied linearly with the scan rate, while Qp and Qp were independent of scan rate. These trends are predicted for thin-layer voltammetric behavior. 

Shinkai futher elaborated his ferrocenyl system and created a colorimetric system capable of visually detecting fluoride binding, thus devising an optical sensor for fluoride. Taking advantage of a redox reaction between the dye molecule methylene blue and ferrocenyl boronic acid, it was possible to visually determine fluoride concentrations. Decolorization of the dye occurs over a 4 x 10- -3 X 10 mM fluoride range (monitored by UV-vis spectroscopy as a decreasing absorbance at 665 nm). 

Many of the chapters in this book have been devoted to various aspects of electroanalytical chemistry at diamond electrodes, for example, the preparation and characterization methods for BDD (Chapter 2), the question of the large potential working range (Chapter 3 for aqueous solution, and Chapter 6 for a wide variety of non-aqueous solutions), the influence of the boron doping levels on the kinetics for redox reactions (Chapters 4 and 5), the characterization and influence of the surface termination (Chapter 7 for hydrogen termination and Chapter 10 for oxygen termination), chemically modified surfaces in general (Chapter 9), metal-modified and ultrasmooth surfaces (Chapter 11), and the use of microelectrodes (Chapter 18) and nanostructured diamond electrode surfaces (Chapter 19). 

Redox reactions. The chemical reduction of metal salts by sodium boron hydride is a common procedure in the preparation of metals and metal alloys. Nanoparticles of iron, FeZrB, FeCoB and FeCoB have been obtained from the corresponding sulphate salts, and NdFeB compounds from neodymium and iron chloride salts. Cobalt nanoparticles have been prepared from cobalt acetate using 1,2 dodecanediol as a mild reducing agent. FePt nanoparticles are produced by the decomposition of iron pentacarbonyl and the reduction of platinum tetrachloride complexes in an organic solvent. Redox reactions can also be produced by electrochemical methods, or in the solid phase. ... 

Diborane reacts with ammonia to form an ionic compound (there are no other products). The cation and anion each contain one boron atom, (a) Predict the identity and formula of each ion. (b) Give the hybridization of each boron atom, (c) Identify the type of reaction that has occurred (redox, Lewis acid-base, or Bronsted acid-base). 

In the area of ion sensing, cation recognition by electrodes containing functionalized redox-active polymers has been an area of considerable interest. Fabre and co-workers have reported the development of a boronate-functionalized polypyrrole as a fluoride anion-responsive electroactive polymer film. The electropolymerizable polypyrrole precursor (11) (Fig. 11) was synthesized by the hydroboration reaction of l-(phenylsulfonyl)-3-vinylpyrrole with diisopinocampheylborane followed by treatment with pinacol and the deprotection of the pyrrole ring.33 The same methodology was utilized for the production of several electropolymerizable aromatic compounds (of pyrrole (12) (Fig. 11), thiophene (13 and 14) (Fig. 11), and aniline) bearing boronic acid and boronate substituents as precursors of fluoride- and/or chloride-responsive conjugated polymer.34... 

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